How old is that tree in your yard?
Use this simple Tree Age Calculator to get an estimate based on trunk size and species.
Different trees grow at different rates, so this tool uses species-specific growth factors to give you a better idea of the tree’s age.
Just measure the circumference of the trunk at chest height (about 4.5 feet or 1.37 meters off the ground), select the tree species, and you’ll get a rough estimate of how many years it has been growing.
It’s a handy way to learn more about the trees around you… whether you’re a gardener, nature lover, or just curious.
🌳 Tree Age Calculator
🌿 How tree age is calculated
Tree age is typically measured by counting the rings in the trunk — but unless you're cutting the tree down, that’s not an option.
Instead, we use a method that estimates age based on growth rate and trunk diameter.
Each tree species has a different average growth rate.
For example, maples and oaks grow at a different pace than pines or firs.
By using the trunk's circumference and a species-specific growth factor, we can estimate how long the tree has been growing.
This method isn't exact, but it's surprisingly accurate for most common tree types.
📏 How to measure your tree
To get the best estimate:
- Measure the circumference of the trunk at chest height (about 4.5 feet or 1.37 meters off the ground).
- Make sure to use a flexible tape measure, and wrap it around the tree at that height.
- Enter the number in inches into the calculator above.
If the trunk isn’t perfectly round (which is common), take a few measurements from different angles and use the average.
🌲 Why estimate a tree’s age?
There are lots of reasons people want to know how old a tree is:
- You may have an old tree in your yard and wonder when it started growing.
- Gardeners and landscapers often want to track tree growth over time.
- It’s a great activity for kids and students who are learning about nature.
- Older trees may require different care or pruning approaches.
Even just knowing whether a tree is 10 years old or 50 years old can help you make better decisions about how to care for it.
📌 Important note
This tool gives you an estimate, not an exact number.
Things like soil type, water availability, sunlight, and local climate can all impact how fast a tree grows.
But as a quick reference, it’s a great way to get a general idea of a tree’s age without special tools or invasive methods.
❓ Frequently Asked Questions
How accurate is this tree age calculator?
This calculator gives an estimated age based on average growth rates for each tree species.
It’s not exact, but it’s usually within a reasonable range — especially if the tree has grown under typical conditions.
Can I use this for any tree species?
Right now, the calculator includes some of the most common North American tree species.
If your tree isn’t listed, you can try choosing the closest match based on tree type and growth rate.
What if I don’t know the tree species?
You can still use the calculator by selecting a tree with a similar growth habit.
For example, if you know it’s a fast-growing tree, you might choose Silver Maple (which grows quickly).
For slower-growing trees, White Oak or Sugar Maple are good stand-ins.
Why do I measure the circumference and not the diameter?
Most people find it easier to measure around the tree with a flexible tape measure.
The calculator then converts that measurement into diameter behind the scenes, using π (pi), to help estimate the tree’s age.
Can I use this tool with metric measurements (centimeters)?
At the moment, the tool works with inches only.
However, you can convert cm to inches by dividing by 2.54.
We may add metric support soon.
Does tree age affect how I care for it?
Yes — older trees may need more regular checkups, less frequent but deeper watering, and care to protect roots.
Knowing the tree's age can help you adjust your care routine.